Radiant ray-sensitive lithographic printing plate precursor

Abstract

A radiant ray-sensitive lithographic printing plate precursor which comprises (a) material or material series which absorbs radiant rays, converts the absorbed radiant rays to heat, and enters into a self-exothermic reaction by the heat, and (b) material or material series which causes a chemical change or a physical change by the reaction heat generated as a result of the self-exothermic reaction.

Description

FIELD OF THE INVENTION[0001] The present invention relates to a lithographic printing plate precursor. Particularly, the present invention relates to a lithographic printing plate precursor from which a printing plate can be directly obtained by plate-making after image information has been, recorded by irradiation of heat mode radiant ray such as operation of an infrared laser etc. based on digital signals or by heat transfer via a thermal head without requiring additional operations.BACKGROUND OF THE INVENTION[0002] The following methods are conventionally known as methods of directly processing a printing plate from digitalized image data without a lith film: (1) a method by electrophotography, (2) a method of using a high sensitivity photopolymer capable of writing with a laser system of comparatively small output which emits blue or green light, (3) a method of using silver salt or a composite system of silver salt and other systems, and (4) a method in which acid is generated ...

AI Technical Summary

Benefits of technology

[0013] A third object of the present invention is to provide a lithographic printing plate precursor which is particularly effective for the first object by using a polymer compound having a functional group which generates a sulfonic acid by heating.

Problems solved by technology

These methods are not necessarily sufficiently satisfactory under the present conditions, although they are very useful in view of the rationalization of the printing process.

For example, in the above method (1) wherein an electrophotographic method is used, image-forming processes such as electric charge, exposure and development are complicated and the apparatus is intricate and large-scaled.

In method (2) of using a photopolymer, since a high sensitivity printing plate is used, handling of a printing plate in a bright room is difficult.

In method (3) of using silver salt, the treatment is complicated and there is such a drawback as silver is contained in a waste solution.

Method (4) requires post-heating and succeeding development, therefore, this method is also accompanied by complicated treatment.

However, this is a so-called development on a printing machine type plate whose non-exposed part of the photosensitive layer is removed during the printing process, and the plate of this type has such a drawback as a fountain solution and printing ink are contaminated.

These plates do not require wet development but, alternatively, rubbing or a process by specific rollers for completing the removal of the silicone layer by laser abrasion is required, therefore, the process is complicated.

In these systems, an image is formed by desulfonating the sulfone group on the surface of a plate by thermal writing, therefore, a development process is unnecessary, but there is such a problem as noxious gas is generated at writing.

However, as the acid generated in this lithographic printing plate precursor is a carboxylic acid, the hydrophilicity thereof is restricted, therefore, durability of the printing plate and sharpness of the printed image are deteriorated.

However, there arises such a problem as a lithographic printing plate using this lithographic printing plate precursor causes contamination under a severe printing condition.

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